Just a few weeks to go, need help on finishing touches!

I'm just over 30 weeks with our girls now, and we've finally settled on Philippa and Vivien (Pip and Vivi for short). Just needing advice on two last touches, namely the spelling of Vivien (i.e., would Vivienne or Vivian be better) and a middle name for Pippa. As far as middles go, we've got the following family/meaningful names in the running as a sister for VivienGray (Gray is a family name):

Is Whitt a family name? If so, I'd go for VivianGray and Philippa Whitt.
If Whitt isn't a family name, then I like that Eve is also a one-syllable middle. PhilippaEve is very classy.

I like Vivienne, but it's pronounced differently to me-- vi-vi-EN versus VIV-i-un. I personally prefer both the look and sound of Vivian, and I like that it matches the rhythm of Philippa, but Vivienne is also a good option.